Figure 4. DeO₂-WP culture system and development of full-term offspring.

(A, B) The culture dish was placed in a sealed plastic bag with a controlled O₂ concentration, placed on a warm plate at 37°C and then covered with aluminum foil during the culture period. (C) Two-cell-stage embryos cultured for 24 h; (D) 8-cell-stage embryos cultured for 48 h and (E) morulae/blastocysts cultured for 72 h on the warm plate. Because the plastic bag was transparent, it was possible to observe embryos directly using an inverted microscope. (F) Mice derived from embryos cultured in the DeO₂-WP culture system. (G) After two or three months, these offspring had grown to adulthood and randomly selected mice were proven fertile by natural mating.